This invention relates to an interrupt information generator and a speech information processor advantageously employed for an electronic musical instrument or a television game device.
The sound source employed in general in an electronic musical instrument or a television game device may be roughly classified into an analog sound source, such as a voltage-controlled oscillator (VCO), a voltage-controlled amplifier (VCA), a voltage-controlled filter (VCF) etc., and a digital sound source, such as a programmable sound generator (PSG) or a zigzag readout type ROM.
The above-mentioned sound source (sampler sound source) stores only sound source data of a pre-set pitch (interval) compressed by compression with, for example, non-linear quantization. Each sound source data is stored in two parts, that is in a formant portion (FR) and a one-period portion (LP) of plural repeated constant period waveforms following the formant portion, as shown in FIG. 4. The formant portion is a signal waveform at the initial stage of sound production proper to each musical instrument, such as an operating sound produced since a key of a keyboard is struck until a hammer hits the string in the case of a piano. During readout of the sound source data, the formant portion is read out first and the one-period portion is read out a plurality of numbers of times.
Since the above sound source data is compressed, and only the required portions, that is the above formant portion and the one-cycle repetitive portion, are extracted and stored, a large quantity of sound source data may be stored in a smaller storage area.
As a general speech information processor for data processing of the sampler sound source, there is known an audio processing unit (APU) 107 consisting of a digital signal processing unit (DSP) 101, a memory 102 and a central processing unit (CPU) 107, as shown in FIG. 5.
In this figure, the APU 107 is connected to a host computer 104, provided in a customary personal computer, a digital electronic musical instrument or a TV game device.
The host computer 104 includes a ROM cassette storing the above-mentioned sound source data, the control program etc. The control program stored in the ROM cassette is read out by the CPU 103 so as to be stored in a working memory 103a therein.
The CPU 103 causes the sound source data to be read out from the ROM cassette and transiently stored in the memory 102, based upon the above-mentioned control program. The CPU 103 also controls the DSP 101 responsive to control by the CPU 103. The DSP 101 causes the sound source data stored in the memory 102 to be read out under control by the CPU 103 and processes the sound source data thus read out with, for example, bit expansion or pitch conversion. The processed sound source data, outputted by the DSP 101, is fed by a D/A converter 105 and thereby converted into analog speech signals which are fed to a speaker unit 106. Thus an acoustic output corresponding to the speech sound data may be produced via the speaker unit 106.
The speech information processor has the continuous playback function of continuously reproducing the sound source data after re-writing a portion of the sound source data, and the multi-loop playback function of repeatedly reproducing each of plural sound source data a pre-set number of times.
If, with the continuous reproduction, the first sound source data and the second sound source data are stored in the memory 102 in succession, the CPU 103 controls the DSP 101 in order to reproduce the data sequentially from the first sound source data first. In the CPU 103 and the DSP 101, the access timing to the memory 102 is pre-set so that DSP 101 accesses the memory 102 twice and subsequently the CPU 103 accesses the memory once. The CPU 103 perpetually polls the end point of the first sound source. The CPU 103 controls the writing in the memory 102 so that, when the end point of the first sound source data is surpassed and the second sound source data starts to be reproduced, the first sound source data is rewritten to and replaced by the third sound source data at the access timing of the CPU 103. The CPU 103 also controls the writing in the memory 102 so that, when the end point of the second sound source data is surpassed and the third sound source data starts to be reproduced, the second sound source data is replaced by the fourth sound source data at the access timing of the CPU 103.
Such control assures continuous reproduction of the sound source data.
If, with the multi-loop playback function, the sound source data of the first formant portion, the sound source data of the first repetitive portion following the sound source data of the first formant portion, the sound source data of the second formant portion and the sound source data of the second repetitive portion following the sound source data of the second formant portion, are stored in succession in the memory 102, the CPU 103 causes the DSP 101 to reproduce the sound source data sequentially beginning from the sound source data of the first formant portion. The CPU 103 perpetually polls the end point of the sound source data of the first repetitive portion. When the end point of the first repetitive portion is detected, the CPU 103 increments a counter, not shown, while causing the DSP 101 to reproduce the sound source data of the first repetitive portion from the outset. Thus the CPU 103 causes the DSP 101 to continuously reproduce the sound source data of the first repetitive portion a plurality of number of times, while incrementing the counter and causing the DSP 101 to reproduce the sound source data of the second formant portion when the count value of the counter reaches a pre-set value.
The CPU 103 perpetually polls the end point of the sound source data of the second repetitive portion. When the end point of the second repetitive portion is detected, the CPU 103 increments the counter, while causing the DSP 101 to reproduce the sound source data of the second repetitive portion from the outset. Thus the CPU 103 causes the DSP 101 to continuously reproduce the sound source data of the second repetitive portion a plurality of number of times, while incrementing the counter and causing the DSP 101 to reproduce the sound source data of the first formant portion when the count value of the counter reaches a pre-set value.
Such control assures reproduction of the sound source data of the repetitive portion a pre-set number of times by way of multi-loop reproduction.
The present assignee has filed, as a related patent application, the EP Publication No. 0543667, and a corresponding patent application in the U.S.A.
If, with the above-described speech information processor employing the APU 107, the sound source data is to be reproduced continuously, the CPU 103 needs to read out the end point of the first sound source data, the second sound source data and so forth frequently and to perpetually poll the end point of the sound source data. On the other hand, if the sound source data is to be reproduced by multi-loop reproduction, the CPU 103 similarly needs to read out the end point of the sound source data of the first repetitive portion, the sound source data of the second repetitive portion and so forth frequently and to perpetually poll the end point of the sound source data.
Such frequent readout of the end point loads the CPU 103 excessively in case of the continuous reproduction or multi-loop reproduction.